Control system for pneumatic conveyors of the tube duct type



Dec. 7, 1965 A. KENNEDY 3,222,577

CONTROL SYSTEM FOR PNEUMATIC CONVEYORS OF THE TUBE DUCT TYPE Filed Oct. 11. l962 INPUT MONOSTABLE OR DELAY 3| MULTIVIBRATOR 38 5w sou-mom 20 2 fikfi LIGHT lnven for BRUCE A. KENNEDY United States Patent 3,222,577 CONTROL SYSTEM FOR PNEUMATIC CONVEY- ORS OF THE TUBE DUCT TYPE Bruce A. Kennedy, Toronto, Ontario, Canada, assignor to Electronic Sound Company, Toronto, Ontario, Canada Filed Oct. 11, 1962, Ser. No. 229,939 5 Claims. (Cl. 317148.5)

This invention relates to improvements in switch controls for use with pneumatic conveyor systems of the type which transport message carriers or articles at comparatively high speeds through tubes.

The type of conveyor system referred to is that type in which a number of stations are interconnected by one or more tubes, the system being used for the transportation of messages and the like. In order to route the message carrier to a desired destination, switches, in the form of guides, are retractably inserted in the tube at the appropriate time and position to guide the carrier into a station.

In providing control means for such pneumatic conveyor systems it is common practice to utilize a variety of relays and electrical contacts to effect switching of the carriers from tube to tube or from tube to receiving station. While such prior systems do achieve some measure of control they suffer from a number of defects which tend to limit their effectiveness and reliability. Thus some moving parts within these systems tend to wear and become inoperative while others require frequent servicing to remain efiective.

Again, it is of importance in providing control means for these tube switches to ensure adequate and constant speed of operation responsive to the switching signal. It will be noted that due to the mechanically interconnected parts and the possibility of Wear that many of the prior tube switch controls are comparatively slow in operation, tending to undesirable drift in closing time.

Accordingly, it is an object of the present invention to provide a tube switch control having a high degree of reliability of operation over a comparatively long period of operation.

It is a further object of this invention to provide a tube switch control which will be rapid in operation thus ensuring positive switching of a carrier at any changeover point in the pneumatic system.

These and other objects and features of this invention will become apparent from the following detailed discussion and accompanying drawings in which like numerals refer to like parts.

In the drawings:

FIGURE 1, is a schematic diagram of one preferred embodiment of a switch control according to the present invention; and,

FIGURE 2 is a diagrammatic representation of the working portion of the delay feature.

Having reference to FIGURE 1 it will be seen that the present invention comprises a DC. power supply indicated generally at 11 and having transformer 12 supplying full wave D.C. circuits 13, 14, and 15 by the use of diode 16. Centre taps 17 and 18 provide the DC. common ground.

Circuit 15 is a constant Voltage D.C. supply controlled by zener diode 19 and supplies a monostable or delay ty-pe multivibrator 20 as well as AND gate 21 with power. The input signal for the control comes from a number of inductive coils 22 arranged in parallel through diodes 23 and connected to the base of transistor 24. Coils 22 are arranged about a tube in a system to be influenced by magnets 25 in carrier 26. The output signal from collector 27 on transistor 24 and through diode 28 forms the input for multivibrator 20.

A pair of transistors 29 and 30 form a monostable Patented Dec. 7, 1965 multivibrator being turned on by negative pulse 31. The time of the multivibrator in the unstable state or on position is determined by the values of resistor 32 and capacitor 33. A positive pulse is supplied through diode 34 in the on position and through diode 35 in the off or stable condition.

Circuit 13 supplies power to a solenoid 36 which when operative, actuates tube switch 37 (not shown) to guide carrier 26 in to the desired tube. Solenoid 36 is in series with a silicon controlled rectifier 38 which is triggered on by a positive impulse through diode 34. An impulse through diode 35 on gate 39 of silicon controlled rectifier 40 impresses a negative impulse on the anode 41 of rectifier 38 thus turning it off and deenergizing solenoid 36. Selenium cell 42 is in parallel with rectifier 38 which protects same from flyback voltage when solenoid 36 is I A signal light 43 is supplied by circuit 14 and is in series with press to break switch 44. A silicon controlled rectifier 45 is in parallel with rectifier 38 and is triggered at the same time thus turning light 43 on.

With reference to FIGURE 2 the method of operation may be better understood by referring to the illustration wherein monostable multivibrator 20 is shown supplied by input 31 from AND gate 21. As has been explained input 31 derives from collector 27 of transistor 24. As carrier 26 containing magnets 25 is moved past the particular arrangement of coils 22, an induced negative signal is transmitted through diodes 23, providing all induced currents are simultaneous, to power transistor 24 producing signal 31 through diode 28 as aforesaid.

The arrangement of silicon controlled rectifiers 29 and 30 produces a monostable multivibrator 20 which as has been previously stated is normally oil in the stable condition and is activated by pulse 31 to the on position for a period of approximately seven seconds in one model, to provide a positive pulse through diode 34. This pulse triggers switch number 2 which is rectifier 38 to turn solenoid 36 on and operate tube switch 37.

The pulse from diode 34 is followed in seven seconds by a similar pulse from diode 36 which through rectifier 40 impresses a negative voltage on anode 41 of rectifier 38 dropping out same. As induced voltage on fiyback from solenoid 36 occurs due to this being turned off, selenium cell 42 allows such excess voltage to flow back to ground and thus protects rectifier 38.

It will be seen that as silicon controlled rectifier 38 is turned on by a pulse from diode 34, rectifier 45 is also triggered which causes light 43 powered by circuit 14, to come on which indicates the presence of carrier 26. Light 43 continues to indicate until switch 44 is manually depressed by an operator when carrier 26 is removed from the system, thus readying same for further use.

From the foregoing it will be understood that the pres ent invention comprises a monostable vibrator having at least two output signals which is in operative relationship a first electrical switch means having on and oh? pSitions responsive to impulses from said bistable multivibrator;

an electrical actuator operable by said first electrical switch means; and pulse generating means including a series of coils associated with diodes to form an AND gate triggering said monostable multivibrator responsible to motion of a permanent magnet past said coils.

2. A switch control comprising:

a monostable multivibrator having at least two output signals;

a bistable multivibrator in operative relationship with said monostable multivibrator;

a first electrical switch means having on and off positions responsive to impulses from said bistable multivibrator;

a second electrical switch means having an on position responsive to said impulse from said bistable multivibrator;

display means response to a signal from said second electrical switch;

an electrical actuator operable by said first electrical switch means; and pulse generating means including a series of coils associated with diodes to form an AND gate triggering said monostable multivibrator responsive to motion of a permanent magnet past said coils.

3. A switch control comprising:

a monostable multivibrator having at least two output signals;

a bistable multivibrator in operative relationship with said monostable multivibrator;

a first electrical switch means having on and off positions responsive to impulses from said bistable multivibrator;

a second electrical switch means having an on position responsive to said impulse from said bistable multivibrator;

display means responsive to a signal from said second electrical switch;

a manual switch in operative relationship with said display means to open said second electrical switch;

an electrical actuator operable by said first electrical switch means; and pulse generating means including a series of coils associated with diodes to form an AND gate triggering said monostable multivibrator responsive to motion of a permanent magnet past said coils.

4. A switch control comprising:

a monostable multivibrator of the solid state type,

having an input and at least two output signals;

a bistable multivibrator of the solid state type in operative relationship with said monostable multivibrator to produce a signal in the on position;

a first electrical switch means having on and otf positions response to impulses from said bistable multivibrator;

an electrical actuator operable by said first electrical switch means; and pulse generating means including a series of coils associated with diodes to form an AND gate triggering said monostable multivibrator responsive to motion of a permanent magnet past said coils.

5. A switch control comprising:

a monostable multivibrator of the solid state type, having an input and at least two output signals;

a bistable multivibrator of the solid state type in operative relationship with said monostable multivibrator to produce a signal in the on position;

a first electrical switch means having on and off positions responsive to impulses from said bistable multivibrator;

a second electrical switch means having an on position responsive to said impulse from said bistable multivibrator;

display means responsive to a signal from said second electrical switch;

a manual switch in operative relationship with said display means to open said second electrical switch;

an electrical actuator operable by said first electrical switch means; and pulse generating means including a series of coils associated with diodes to form an AND gate triggering said monostable multivibrator responsive to motion of a permanent magnet past said coils.

No references cited.

SAMUEL BERNSTEIN, Primary Examiner. 

1. A SWITCH CONTROL COMPRISING: A MONOSTABLE MULTIVIBRATOR HVING AT LEAST TWO OUTPUT SIGNALS; A BISTABLE MULTIVIBRATOR IN OPERATIVE RELATIONSHIP WITH SAID MONOSTABLE MULTIVIBRATOR; A FIRST ELECTRICAL SWITH MEANS HAVING ON AND OFF POSITIONS RESPONSIVE TO IMPULSES FROM SAID BISTABLE MULTIVIBRATOR; 